Failover is the process in which a node in a cluster is declared as unavailable and a replica vBucket is enabled.

Information is distributed around a cluster using a series of replicas, which are complete copies of the data stored in the bucket and kept within the Couchbase Server Cluster. For Couchbase buckets, you can configure a number of replicas.

In the event of a failure in a server (either due to transient failure or for administrative purposes), use a process called failover to indicate that a specific node within the cluster is no longer available and to enable the replica vBuckets for the failed over server node.

The failover process contacts each server that was acting as a replica and updates the internal table that maps client requests for documents to an available Couchbase Server.

Failover can be performed manually or automatically using the built-in automatic failover process. Auto failover acts after a preset time when a node in the cluster becomes unavailable.